HOS15 interacts with the histone deactetylase HDA9 and the Evening Complex to epigenetically regulate the floral activator GIGANTEA

First author: Hee Jin Park; Affiliations: Konkuk University (建国大学): Seoul, Korea

Corresponding author: Woe-Yeon Kim

In plants, seasonal inputs such as photoperiod and temperature modulate the plant's internal genetic program to regulate the timing of the developmental transition from vegetative to reproductive growth. This regulation of the floral transition involves chromatin remodeling, including covalent modification of histones. Here, we report that HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENE 15 (HOS15), a WD40 repeat protein, associates with a histone deacetylase complex to repress transcription of the GIGANTEA (GI)-mediated photoperiodic flowering pathway in Arabidopsis thaliana. Loss of function of HOS15 confers early flowering under long-day conditions due to elevated GI expression. LUX ARRHYTHMO (LUX), a DNA binding transcription factor and component of the Evening Complex, is important for the binding of HOS15 to the GI promoter. In wild type, HOS15 associates with the Evening Complex components LUX, EARLY FLOWERING 3 (ELF3), and ELF4 and the histone deacetylase HDA9 at the GI promoter, resulting in histone deacetylation and reduced GI expression. In the hos15-2 mutant, the levels of histone acetylation are elevated at the GI promoter, resulting in increased GI expression. Our data suggest that the HOS15-EC-HDA9 histone-modifying complex regulates photoperiodic flowering via the transcriptional repression of GI.

在植物中，季节性的环境信号如光周期和温度会调节植物内部的遗传程序，从而调控植物从营养生长向生殖生长的转变。成花转变的调控涉及染色质重塑，其中包括组蛋白的共价修饰。本文，作者报道了一个WD40重复蛋白HOS15与一个组蛋白脱乙酰酶复合物一起抑制GI的转录，从而介导拟南芥中的光周期开花途径。HOS15的功能缺失突变体会在长日照的条件下通过增加GI的表达促进提早开花。一个DNA结合转录因子LUX蛋白，同时它也是EC复合体的组份之一，有助于HOS15结合到GI启动子上。在野生型拟南芥中，HOS15与EC复合体组份LUX、ELF3和ELF4以及组蛋白脱乙酰基酶HDA9一起在GI启动子区发挥作用，通过组蛋白脱乙酰作用降低GI的表达量。在hos15-2突变体中，GI启动子上的组蛋白乙酰化水平增加，导致GI表达水平上升。本文的研究揭示了HOS15-EC-HDA9组蛋白修饰复合体通过GI的转录抑制调控光周期开花。

p.s. 同期评论文章：http://www.plantcell.org/content/early/2019/01/22/tpc.19.00039

doi: https://doi.org/10.1105/tpc.18.00721

Journal: Plant Cell

First Published: January 03, 2019